Technical field

[0001] The present invention discloses the production of MXene reinforced Kondagogu gum composite via sustainable and economic “green” processes using aqueous solutions to replace organic solvents.

Background art

[0002] Plant gums have particular importance and have been used for years for various purposes. Natural products of plant origin are gaining a reputation in terms of biological wealth. Tree gums are used as stabilizing, suspending, gelling, emulsifying, thickening, binding, and coating agents. Apart from various industrial applications, tree gums have been also used as food additives and have safe use as pharmaceutical substances.

[0003] A critical feature of tree gums is that they are non-toxic and are biodegradable. One such product is an exudate tree gum, regionally called gum Kondagogu (Cochlospermum gossypium), belonging to the Bixaceae family. Experimental work carried out on this gum has resulted in assigning a separate identity to this gum compared to the well-established and commercially exploited gums such as Arabic gum, Karaya gum, Tragacanth gum, Ghatti gum, etc.

[0004] The Kondagogu gum has unique physicochemical properties as compared to other tree gums. Proximate analysis of the gum indicates that it has high volatile acidity and water-binding (hydrogel property) capacity. Among natural gum exudates, gum Kondagogu possesses an essential function due to their physical, chemical, structural, morphological, rheological properties, and interaction with other materials [1 , 2],

[0005] The Smith degradation analysis indicated that the backbone structure of Kondagogu gum to be of z-D-GalpA-(1 -^-4)-a-L-Rhap and can be grouped under rhamno- galacturonans type of gum, as it is rich in rhamnose, galactose, and uronic acids residues [2]. [0006] The XRD pattern of the native Kondagogu gum exhibits an entirely amorphous structure. Kondagogu gum showed signified differences in their properties pertaining to elemental composition, sugar composition, amino and fatty acid profile compared to other established tree gums such as Arabic gum, Karaya gum and Tragacanth gum.

[0007]The major functional groups identified from FT-IR spectrum include 3431 cnr ¹ (- OH), 1731 cm- ¹ (CH ₃ CO-), 1632 cm’ ¹ (-COO-), 1429 cm- ¹ (-C00), 1249 cm’ ¹ (-CH3CO) [2], [0008] Scanning electron microscopy (SEM) of native and deacetylated Kondagogu gum has shown that the native form of the gum has varying particle sizes. Deacetylated gum was found to be fibrilar, indicating the loss in particulate morphology observed in the native state of the gum, suggesting that acetyl groups are essential in the structural integrity of the gum for particulate appearance in the native form [2],

[0009] DSC analysis indicated that the thermal glass transition temperature of Kondagogu gum is 32.5 °C [2], TGA analysis showed that the decomposition pattern of deacetylated Kondagogu gum was distinctly different from that of native Kondagogu gum, suggesting that deacetylated form of gum was more thermally stable than its native form [2], [0010] The elemental analysis (C, H, N, and S) of Kondagogu gum was determined to be 34.97 %, 5.58 %, 0.229 %, and 0.128 % (w/w), respectively [2], The mineral element composition of Kondagogu gum indicated that calcium, potassium, and sodium were found to be higher than aluminum, cadmium, cobalt, copper, chromium, iron, lead, manganese, nickel, and zinc [2, 3],

[0011] The high uronic acid and aspartic acid content of Kondagogu gum make this gum more acidic gum. The lipid content of Kondagogu gum was determined to be 2.2 g% by gravimetric analysis. Kondagogu gum contains 84.4 % (w/w) of saturated fatty acid and 15.6 % (w/w) of unsaturated fatty acids. Stearic acid (C18:0) (37.25 % (w/w)) was the primary fatty acid present in the gum [4],

[0012] Among the unsaturated fatty acids, linoleic acid (3.45 % (w/w)) and y-linolenic acid (0.54 % (w/w)) were detected in Kondagogu gum. The amino acids and fatty acids profiles can be used as a molecular marker for distinguishing Kondagogu gum from other tree gums [4], [0013] The rheological measurements performed on the Kondagogu gum suggest that above 0.6 % (w/w), it shows a Newtonian behavior and shear rate thinning behavior as a result of gum concentration [1],

[0014] The two different concentrations of Kondagogu gum (1 % and 2 %) in aqueous and 100 mM NaCI solutions indicated that viscous modulus (G ^z ) has a weak frequency dependence and viscous modulus was always higher than elastic modulus (G ^zz ). This behavior is typical of a gel-like matrix, and the addition of NaCI decreases the gel strength of Kondagogu gum polysaccharides [1],

[0015] In the presence of 100 mM NaCI, Kondagogu gum showed a more liquid like structure and the oscillatory data are as expected for a semi-dilute to concentrated solution of entangled, random coil polymers [1],

[0016] A crossover value of G ^z and G ^zz was observed at a frequency of 0.432 Hz for 1 % and 1.2 Hz for 2% solution of native gum, indicating a predominantly liquid to solid-like behavior. A crossover value of 2.1 Hz for 1 % and 1 .68 Hz for 2% gum in 100 mM NaCI solution suggests a more significant elastic contribution [1],

[0017] The zeta potential of the native and deacetylated Kondagogu gum in aqueous solutions was recorded to be -23.4 and - 37.4 mV, respectively. Intrinsic viscosity of native Kondagogu gum (32.68 ± 0.23 dL g ^_1 ) was found to be lower than that of deacetylated gum (59.34 ± 1.38 dL g- ¹ ) [5],

[0018] The intrinsic viscosity of the native and deacetylated Kondagogu gum was established to be [/)] = 9.75 x10’ ⁴ Mw ^{0 80} (dl/ g) and 9.32 x 1 O’ ⁴ Mw ^{0 76} (dl/ g), respectively [5].

[0019] The Mark-Houwink-Sakurada exponent (cr) is related to shape of macromolecule and has an intimate relationship with the degree of rigidity and solvation ability of a polymer. The a value of 0.80, 0.76 for Kondagogu gum (native and deacetylated, respectively) suggests that its macromolecular nature assumes a more expanded conformation and behaves as random coil in good solvent (NaCI, 1 M solution) [5], [0020] The biosorption of Pb ²⁺ , Cd ²⁺ , Ni ²⁺ and total Cr by Kondagogu gum was found to be influenced by contact time, pH of the medium, initial concentration of the metal ions and biopolymer content. Biosorption mechanisms of heavy metals by Kondagogu gum mainly involve complexation between heavy metal ions and gum, adsorption, surface micro-precipitation and ion- exchange phenomena [6, 7],

[0021] Non-food applications of Kondagogu gum are explored in many potential fields, such as environmental, energy, food packaging, biosensor, and biomedical [8], Many natural polymers have earlier been explored as blending composites with 2D materials (graphene, carbon nanotubes, and their analogous).

[0022]Tree gums alone suffer from weak mechanical strength, low flexibility, and brittle nature and, therefore, cannot be used in any form. The composites and nanostructures prepared via intercalating Kondagogu gum with graphene oxide may be employed as materials for biodegradable food packaging. Also biomedical, and energy harvesting applications of these material have been studied [9 and 10],

[0023] The electrospinnability of blend solutions of Kondagogu gum with other natural/synthetic polymers have also been studied [11 , 12, 13], The adsorption/removal of nanoparticles and toxic heavy metal by functionalized Kondagogu gum have been reported [14],

[0024] The chemical modification of Kondagogu gum such as by DDSA (dodecenyl succinic anhydride) to enhance the solution, electrospinnability, mechanical, encapsulation, and antibacterial potential of the composite material is also known [15, 16].

Principle of the invention

[0025] The present invention is described in accordance with the appended claims.

[0026] The objective of the invention is to prepare reinforced Kondagogu gum composite that has enhanced mechanical properties.

[0027] To achieve the objective mentioned above, the problem is solved in an embodiment by a method of preparing composites using Kondagogu gum (with an additive MXene, (TisC2T _x ), a versatile 2D inorganic filler.

[0028] The gum is processed into powder form by crushing the chunk of gum Kondagogu in a tabletop mixer/grinder. The milled form is sieved using a 250 pm sieve to collect the powdered sample. The powdered sample should be stored in a desiccator to avoid contact with air to reduce moisture absorption. [0029] The purified Kondagogu gum (1 g; grade III, non-edible gum, GK enterprises, Hyderabad, India) was dissolved in 100 mL of deionized water solution to obtain a Kondagogu gum solution containing 1.0 wt%. It is preferable to prepare the Kondagogu gum solution (1 wt.%) by keeping the solution over a magnetic stirrer at room temperature for 30 minutes.

[0030] MXene (TisC2T _x ) was prepared by selectively etching the Al layer in the precursor Ti3AIC2, using LiF/HCI solution as an etchant, based on the disclosed method. The Purified MXene is characterized by several ways to conform to their competition and purity. MXene procured from MedTech Diamond LLC, 18974 Pennsylvania, USA was used during experiments.

[0031] The degradation studies of the MXene reinforced gum composite have shown that the developed material is a sustainable and eco-friendly composite.

[0032] The preparation of composites using Kondagogu gum and MXene was followed by the mixing of varying concentrations (0.05. 0.1 , 0.25, 0.5 and 0.75 wt. %) of MXene with 1 wt. % of Kondagogu gum, the weight ratio between the MXene and Kondagogu gum thus being (0.05, 0.1 , 0.25, 0.5, 0.75) : 1.

[0033] The prepared MXene@Tree Kondagogu Gum composite with enhanced physicochemical properties may be used for the fabrication of functionalized 3D sponges, films and membranes for many potential applications, such as oil/water separation, energy and environmental appliances.

The present invention will now be described in further details with reference to the following examples and representative drawings.

Brief description of the drawings

[0034]

Figure 1 is a photography which shows the specimen sample for Kondagogu gum (Grade III). The sample is procured from the gum suppliers from India (GK enterprises, Hyderabad, India).

Figure 2 shows the molecular weight profile of Kondagogu gum estimated using gel permeation chromatography linked to multiangle laser light scattering (GPC-MALLS). The parameters are assessed Mw (weight-average), Mn (number-average) and z-average (M _z ), and average mean square radius moments (Rn, Rw, and Rz all in nm). This sample was used for the preparation of the composite.

Figure 3 shows the schematic illustration of preparation of MXene reinforced Kondagogu gum composite (Mxene @ Tree Kondagogu Gum) and the functional group interaction.

Figure 4a shows scanning electron microscopy image of Kondagogu gum (pristine sample) with magnification of 1 ,000.

Figure 4b shows scanning electron microscopy image of the MAX phase of TisAIC2 with magnification of 5,000.

Figure 4c shows scanning electron microscopy image of the multilayered TisC2T _x produced by etching of MAX phase using LiF and HCI with magnification of 25,000.

Figure 4d shows scanning electron microscopy image of MXene@Tree Kondagogu Gum composite (KOG/MX-4) with magnification of 22,070.

Figure 5 shows the XRD patterns of pristine Kondagogu gum (Figure 5b), MXene (Figure 5a), and MXene@Tree Kondagogu Gum composite (KOG/MX-4) (Figure 5c) analyzed by XRD analysis.

Figure 6 shows the ATR-FTIR spectra of MAX phase (Figure 6a), MXene (Figure 6b), Tree gum Kondagogu (Figure 6c), and MXene reinforced gum composite (KOG/MX-4) (Figure 6d), respectively.

Figure 7a to 7c shows the XPS elemental content analysis of Tree gum Kondagogu (KOG) (7a), presenting the C1 s and 01 s spectrs indicating the functional groups; MXene (7b), indicating the high-resolution spectre of Ti 2p, Ti-C (2p3/2), Ti (II) (2p3/2), Ti-0 (2p3/2), Ti-C (2p1/2), Ti (II) (2p1/2) and Ti-0 (2p1/2) bonds, and C1s, O1s and F1s spectres, respectively and KOG/MX-4 (7c) indicating the possible interaction of Mxene and tree gum Kondagogu, respectively.

Figure 8 shows the thermal stabilities of pristine MAX phase (curve 8a), Mxene (curve 8b), tree gum Kondagogu (curve 8c), and MXene reinforced gum composite (KOG/MX- 4) (curve 8d) as measured by TGA.

Figure 9 shows the biochemical oxygen demand (BOD) analysis curves for the pristine tree Kondagogu gum, and MXene reinforced gum composite (KOG/MX-4). Examples of Embodiment

Samples and test methods

[0035] The authenticated Kondagogu gum (Grade III) of Cochlospermum gossypium was obtained from GK enterprises, Hyderabad, a gum exporting company from India. The sample was grey. The sample was cleaned and kibbled using pestle and mortar and later an electric crusher to make a homogeneous powder form. The whole powder form was sieved by 250 .m size mesh and stored under a sealed airtight box to avoid moisture absorption. For subsequent analysis, this powder form was then used. [0036] The proximate analysis, water binding capacity, specific rotation, intrinsic viscosity, sugar composition, amino acid and fatty acid profile, mineral compositions, functional group characterization, structural analysis and solution properties was determined according to the method described in the literature [1 ,2, 3, 4], The parameters thus determined were specified in Table 1.

Table 1 : Analytical data for various parameters determined for Tree Kondagogu Gum [0037] The molecular weight of the Kondagogu gum was determined by the method described in the literature [17], The GPC-MALLS (gel permeation chromatography coupled with multiangle light scattering) is used to determine the molecular weight of Kondagogu gum. Briefly, Kondagogu gum (0.2 wt.%) were prepared in 0.1 M NaNOs solution and left overnight on a roller to complete dissolution of the samples. The GPC (gel permeation chromatography) system consisted of a Suprema 3000 column with these specifications (dimensions: 300 mm; 8 mm; bead size: 10 pm and pore size: 100 pm). A guard column (Polymer Standards Service GmbH) protected the column. The flow rate was set to 0.5 mL/min using a Waters Corporation HPLC pump in conjunction with a Rheodyne 7125 model injection system (loop volume 200 pL). A Dawn DSP Laser Photometer and OPTILAB DSP Interferometric Refractometer (Wyatt Technology Corporation) were used as detectors. The gum samples were filtered through 0.45 pm syringe filters before being injected into the HPLC column. All measurements were performed in triplicate. The molecular mass distributions of Kondagogu gum and rms radius moments were determined using the designated Astra software for Windows (4.90.08, QELSS 2. XX). The molecular weight (Mw) thus determined was 1.1 x10 ⁶ g/mole.

The molecular mass distributions such as the number average, Mn; and z-average molecular mass, Mz were 8.2x10 ⁵ g/mole and 1.4x10 ⁶ g/mole, respectively.

The rms radius moments thus determined were: Rn (82.9 nm); Rw (90.7 nm) and Rz (96.3 nm), respectively.

[0038] Preparation of MXene (Ti3C2T _x ) from the MAX phase:

MXene (TisC2T _x ) was prepared by selectively etching the Al layer in the precursor TisAIC2, using LiF/HCI solution as an etchant, based on the method described in the literature [18] In brief, LiF (8 g) was dissolved in 100 mL HCI solution (9 M) by stirring for 5 min in an airtight PTFE bottle. TisAIC2 (5 g), purified by 50 mL HCI solution (1 M) for one h, were added particularly slowly into the above LiF/HCI solution under stirring. The mixed solution was then reacting at 35 °C for 36 h under magnetic stirring. The resulting suspension was washed with deionized water and subsequently centrifugated at a speed of 3500 rpm until pH reached 6.0 and the supernatant became dark in colour. [0039] Preparation of KOG/MX-x

The purified Kondagogu gum (1 g) was dissolved in 100 ml_ of deionized water to obtain a Kondagogu gum solution with a content of Kondagogu gum 1 wt %. To fabricate the MXene@Kondagogu blend solution, the MXene/Kondagogu gum solution with the same solid content and different ratio of MXene/Kondagogu gum was mixed according to Table 2. In brief, a specific volume MXene solution (sonicated for 30 min) was uniformly dispersed into Kondagogu gum solution (1.0 wt. %) by stirring for 10 min and after that, the solution was kept in a magnetic stirrer for 24 h. The pH of the solution was noted to be pH=7.0. Then, the colloidal suspension was filtered by the vacuum pump to obtain MXene/Kondagogu gum solution with different MXene content.

Table 2

[0040] Gum Hydrocolloids are high molecular weight biopolymers and are water-soluble due to polar groups in the chains. When dissolved in water, they form viscous dispersions and act as thickening/gelling agents even at higher concentrations. Kondagogu gum shows high viscosity and gelling properties at a more than 1 wt % concentration [1 ], In this context solution with concentration of Kondagogu gum of more than 1 wt % to make the composite is restricted. At the same time, solution with concentration of Kondagogu gum of less than 1 wt.% cannot disperse the MXene used at various concentrations to make the composite, which was observed during experiments. The weight of Kondagogu gum and MXene in different composites was determined based on the homogeneity of mixing, settling time, viscosity, precipitating tendency, gelling properties, and stability of the composites.

[0041] Excellent and uniform dispersion of MXenes is required for good mechanical strength, and conductivity, by the interaction between gum structures (a variety of functional groups inherently present in Kondagogu gum such as carboxyl (-COO), hydroxyl (OH-), ether (C-O-C), acetyl (CH3CO-), aliphatic (-CH) and carbonyl (-C=O)) with MXene flakes (surface functional groups (-0, -OH, and -F)) via van der Waals forces, electrostatic interactions, and hydrogen bonding. Pristine MXene otherwise has the drawbacks of easy restacking, low flexibility, and poor stability in an oxygen atmosphere. Due to synergistic effect between the MXene and gums, a conductive reinforcement polymer additive is prepared.

The composite also showed excellent physicochemical properties.

Example 1 : Preparation of MXene@Tree Kondagogu Gum composites from KOG/MX-x

[0042] Various samples prepared form the blend mixture of KOG/MX-x, see KOG/MX-1 , KOG/MX-2, KOG/MX-3, KOG/MX-4 and KOG/MX-5 were freeze-dried to get the corresponding composites. A series of experiments was undertaken, which demonstrated formation of MXene@TGKC composites. However, the following characterization was confirmed to be the best composite formation as selected among them. The KOG/MX-4 is according to experimental evidence supported by spectroscopic and microscopic analysis, such as XRD, SEM, XPS, FTIR, etc., and compared with other composites of MXenes, the best variant of composite formed between MXene and Kondagogu gum. The observation and analysis pertaining to dispersibility, particle size distribution, settling time, and homogeneous distribution were tested to confirm that KOG/MX-4 preparation is the most suitable combination for keeping the dispersibility and colloidal stability of MXene in aqueous gum solution. Additionally, XRD, UV-vis spectroscopy, dynamic light scattering study, HR-TEM analysis, and XPS analysis.

Example 2: Characterization of MXene@Tree Kondagogu Gum composites (KOG/MX-4) [0043] Figure 1 shows the specimen sample (tree Kondagogu gum of Grade III). Figure 2 shows the molecular weight analysis of tree Kondagogu gum used. Figure 3 shows the schematic illustration of the formation of MXene@Tree Kondagogu Gum composite. TisC2T _x MXenes were synthesized by chemical etching of the Al atoms from their parent MAX phases, TisAIC2.

[0044] Scanning electron microscopy images of (a) Kondagogu gum (pristine sample), (b) the MAX phase of TisAIC2, (c) the multilayered TisC2T _x produced by etching of MAX phase using LiF and HCI; and (d) MXene@Tree Kondagogu Gum composite (KOG/MX- 4) are presented in Figure 4 (a, b, c and d), respectively. The Kondagogu gum shows (Figure 4a) elongated sheets like strictures after purification. As revealed in Figure 4b, the MAX phase of TisAIC2 is relatively stable and structurally the layered hexagonal as described earlier. According to the literature [19, 20], we also used LiF and HCI for etching the MAX phase (TisAIC2) to produce Ti3C2Tx MXene. The SEM picture of TisC2T _x MXene (Figure 4c) shows the densely packed nanosheets into a highly ordered hierarchical structure with layered morphology. The interaction between Kondagogu gum and MXene resulted in a uniform composite (KOG/MX-4) presented in Figure 4d. The KOG/MX-4 composite appears as a nacre-like well-ordered layered structure without showing any agglomeration.

[0045] Figure 5 shows the structural information of Kondagogu gum, MXene, and MXene@Tree Kondagogu Gum composite (KOG/MX-4) using XRD analysis. XRD analysis indicates the conversion of the MAX phase to MXene and their intercalation efficiency. The prominent diffraction peak at 8.81 ° corresponds to the indexed phase as (002) peak of TisC2T _x MXene, indicating its interlayer d-spacing of 1.01 nm. In the XRD pattern of KOG/MX-4, the TisC2T _x (002) peak shifted to 8.25 °, specifying that there is a change in interlayer spacing which is accounted to be 1 .35, compared to the MXene. This is attributed to the intercalation of Kondagogu gum into the interlayer spaces between TisC2Tx MXene sheets.

[0046] Figure 6 shows the ATR-FTIR spectra of MAX phase (Figure 6a), MXene (Figure 6b), tree gum Kondagogu (Figure 6c) and KOG/MX-4 composite (Figure 6d). The absorption bands at 3434, 1078, 1384, and 1631 cm’ ¹ assigning to -OH, C-O, and C=O, respectively [1 ,2,3], This indicates that the abundant oxygen functionalities are present in MXene (Figure 6b). The various functional groups such as -OH, -C=O, C-H (stretching), -COOH-, -CH2 (twisting), and -C-0 (stretching) vibrations are documented in tree gum Kondagogu gum (Figure 6c) [2, 3], As shown in Figure 6d, there has been potential evidence of intermolecular hydrogen bonding occurring between the functional group interaction of tree gum Kondagogu with MXene. The predominant changes were reducing the intensity of the -OH group of Kondagogu gum at 3440 cm’ ¹ and the disappearance of the -C=O group at 1700 cm’ ¹ in the KOG/MX-4 (Figure 6d).

[0047] Figure 7 shows the XPS analysis of tree gum Kondagogu (Figure 7a), MXene (Figure 7b), and KOG/MX-4 (Figure 7c), respectively. The formation of composite between Kondagogu gum and MXene (KO/MX-4) enhances the intensity of the C element. It is expected to see in the high-resolution C 1s spectra of the interaction between Kondagogu gum and MXene indicating the presence of Ti-C-0 (282.8 eV), Ti-C (281.8 eV), C-C (284.8 eV (Figure 7c). The C-C (284.8 eV) and C-0 (286.3eV), C- O-C (287.8eV) are the assigned functional groups with their binding energies of Kondagogu gum. The Ti 2P in the pristine MXene is 16.3 %, whereas the composite recorded 2.1 %.

From XPS analysis, it is observed that Al is selectively etched from Ti3AIC2 to prepare Ti3C2Tx with traces of F 1 s at 684.5 eV respectively (KOG/MX-4 at Figure 7c and MXene at Figure 7b). The addition of tree gum Kondagogu into MXene results in the improved intensity of C element. The C/Ti atomic ratio in KOG/MX-4 is higher than that in pure MXene (see Table 3), indicating the increased fraction of organic ingredients.

[0048] Table 3: The peak ratio (%) of C 1 S, F 1 S, 01 S, and Ti 2P for MXene, Kondagogu gum, and MXene@Tree Kondagogu Gum composite (KOG/MX-4).

Table 3 The high-resolution 0 1s XPS spectra should show the presence of TiO2 (529.7 eV), Ti-C-Ox (530.8 eV), Ti-C- (OH)x (532.0 eV) [19], In the present investigation, the changes in O1s spectra were observed, indicating the broadening of the peak when the interaction between MXene and Kondagogu gum for composite formation. Probably it appears to be the formation of Ti-C-OH/TiO2 as reported elsewhere [19],

The Ti 2p high-resolution spectra on MXene are identical to those reported in literature

[20], However, in our present investigation, the Ti 2p peak consists of TiC, TiF, and TiOx components; therefore, it is a complex multicomponent system.

The MXene F1 s spectrum has a strong signal at -685.2 eV, corresponding to fluorine binding to the Ti carbide and creating an F— Ti— C bond. The F1 s signal at a slightly higher binding energy of -687.5 eV might even indicate a fluorine bridging atom (C-Ti-F-Ti-C)

[21], We can see this bond also in the Ti2p peak. During the composite formation, the peak ratio (%) has significantly increased the F1s higher energy associated with increased fluorine bridging atoms (C-Ti-F-C) in KOG/MX-4 (see the Table 4). Thus, the Ti bonding has significantly changed in the composite material.

Table 4

The detailed study of Ti2p indicates the presence of TiC is not to be affected by the composite preparation. On the contrary, the TiF is significantly reduced.

[0049] Figure 8 shows the thermal stabilities of pristine MAX phase, MXene, Kondagogu gum and KOG/MX-4 as were measured by TGA. Pristine MAX phase MXene did not show much weight loss, and its degradation curve is presented in Figure 8 a and Figure 8 b, respectively. The MXene (curve 8b, Figure 8) started to decompose at 118.8 °C, and this weight loss is attributed to the removal of organic groups on the surface of the MXene layer. The decomposition of composite (KOG/MX-4) occurred at 277.6 °C and was much higher than pristine MXene. The GK is comparably stable to a composite (curve 8c, Figure 8). The result indicates the decomposition of KOG/MX-4 (curve 8d, Figure 8). The decomposed products of MXene, including TiO2 and titanium carbide phases are shown as residue at 700 °C (see the Table 5).

Table 5: TGA data under the nitrogen condition of each sample. (10 °C/min, 2-5mg; errors ± 0.5 wt.%, ± 1 °C)

[0050] Figure 9 shows the biochemical oxygen demand (BOD) analysis curves for the pristine Kondagogu gum and MXene reinforced gum composite (KOG/MX-4). In this process, the biopolymers are broken into more minor constituents by aerobic microbial organisms through metabolic or enzymatic processes and finally converted to carbon dioxide. The results indicate that BOD for Kondagogu gum was slightly higher during the whole measured period than in the case of the (KOG/MX-4) composite. The final value of 1846 ± 16.7 mg O2 L’ ¹ for Kondagogu gum and 1578± 34.5 mg O2 L’ ¹ for the (KOG/MX- 4) composite was achieved after 28 days. In the early stage, various functional interactions on the KOG/MX-4 composite decelerate the action of microorganisms on the material, thereby reducing the rate of degradation. Overall, the results suggest that the KOG/MX-4 composite biodegraded almost similarly (90%) to the Kondagogu gum (92%) over 28 days, though the initial degradation was slow for the composite. The composite is environmentally biodegradable in nature.

[0051] In the method for production of MXene reinforced Kondagogu gum composite according to the invention, a powder prepared from Kondagogu gum having particles with all dimensions under 250 pm is dissolved in deionized water and Kondagogu gum solution containing 1.0 wt % of Kondagogu gum is prepared. To this solution, a TisC2T _x is added, whereby the weight ratio between the TisC2T _x and Kondagogu gum is (0.05 to 0.75) : 1 , preferably 0.5 : 1 , and the solution thus prepared is mixed and filtered, whereby interactions between functional groups of Kondagogu gum (carboxyl (-COO), hydroxyl (OH-), ether (C-O-C), acetyl (CH3CO-), aliphatic (-CH) and carbonyl (-C=O)) and functional groups of TisC2T _x (-0, -OH, and -F) bond TisC2T _x to Kondagogu gum by means of van der Waals forces, electrostatic interactions, and hydrogen bonding. The solution is freeze-dried to prepare MXene@Tree Kondagogu Gum composite. The composite has a form of homogenous powder and its suspension in aqueous phase was found to be stable for more than 6 months.

[0052] The composite thus prepared contains Kondagogu gum and TisC2T _x in a weight ratio of (0.05 to 0.75) : 1 , preferably 0.5 : 1 , whereby TisC2T _x is bonded to the Kondagogu gum by means of van der Waals forces, electrostatic interactions, and hydrogen bonding formed between functional groups of Kondagogu gum (carboxyl (-COO), hydroxyl (OH-), ether (C-O-C), acetyl (CH3CO-), aliphatic (-CH) and carbonyl (-C=O)) and functional groups of Ti ₃ C ₂ T _x (-O, -OH, and -F).

References

[1 ] Vinod, V. T. P. et al. (2008) ‘Compositional Analysis and Rheological Properties of Gum Kondagogu (Cochlospermum gossypium): A Tree Gum from India’, Journal of Agricultural and Food Chemistry, 56(6), pp. 2199-2207. doi: 10.1021 /jf072766p.

[2] Vinod, V.T.P. et al. (2008) ‘Morphological, physico-chemical and structural characterization of gum kondagogu (Cochlospermum gossypium): A tree gum from India’, Food Hydrocolloids, 22(5), pp. 899-915. doi: 10.1016/j.foodhyd.2007.05.006.

[3] Vinod, V .T. P and Sashidhar, R. B (2010) ‘Surface morphology, chemical and structural assignment of gum Kondagogu (Cochlospermum gossypium DC.): An exudate tree gum of India’, Indian Journal of Natural Products and Resources, 1 (2), pp. 181-192. httD://noDr.niscor.res.in/handle/123456789/9825.

[4] Vinod, V. T. P. et al. (2010) ‘Comparative amino acid and fatty acid compositions of edible gums kondagogu (Cochlospermum gossypium) and karaya (Sterculia urens)’, Food Chemistry, 123(1), pp. 57-62. doi: 10.1016/j.foodchem.2010.03.127.

[5] Vinod, V. T. P. and Sashidhar, R. B. (2009b) ‘Solution and conformational properties of gum kondagogu (Cochlospermum gossypium) - A natural product with immense potential as a food additive’, Food Chemistry, 116(3), pp. 686-692. doi: 10.1016/j.foodchem.2009.03.009.

[6] Vinod, V. T. P., Sashidhar, R. B. and Sreedhar, B. (2010) ‘Biosorption of nickel and total chromium from aqueous solution by gum kondagogu (Cochlospermum gossypium): A carbohydrate biopolymer’, Journal of Hazardous Materials, 178(1-3). doi: 10.1016/j.jhazmat.2010.02.016.

[7] Vinod, V. T. P., Sashidhar, R. B. and Sukumar, A. A. (2010) ‘Competitive adsorption of toxic heavy metal contaminants by gum kondagogu (Cochlospermum gossypium): A natural hydrocolloid’, Colloids and Surfaces B: Biointerfaces, 75(2). doi: 10.1016/j.colsurfb.2009.09.023.

[8] Padil, V. V. T. et al. (2018) ‘Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields’, Biotechnology Advances, 36(7), pp. 1984-2016. doi: 10.1016/j.biotechadv.2018.08.008.

[9] Venkateshaiah, A., Cheong, J. Y., Shin, S.-H., et al. (2020) ‘Recycling non-food-grade tree gum wastes into nanoporous carbon for sustainable energy harvesting’, Green Chemistry, 22(4), pp. 1198-1208. doi: 10.1039/C9GC04310A.

[10] Venkateshaiah, A., Cheong, J. Y., Habel, C., et al. (2020) ‘Tree Gum-Graphene Oxide Nanocomposite Films as Gas Barriers’, ACS Applied Nano Materials, 3(1), pp. 633-640. doi: 10.1021/acsanm.9b02166.

[11] Padil, V. V. . et al. (2020) ‘Electrospun fibers based on carbohydrate gum polymers and their multifaceted applications’, Carbohydrate Polymers, 247, p. 116705. doi: 10.1016/j.carbpol.2020.116705.

[12] Padil, V. V. T. et al. (2016) ‘Electrospun fibers based on Arabic, karaya and kondagogu gums’, International Journal of Biological Macromolecules, 91 , pp. 299-309. doi: 10.1016/j.ijbiomac.2016.05.064.

[13] Silvestri, D. et al. (2019) ‘Production of electrospun nanofibers based on graphene oxide/gum Arabic’, International Journal of Biological Macromolecules, 124, pp. 396-402. doi: 10.1016/j.ijbiomac.2018.11.243.

[14] Padil, V. V. T. et al. (2018) ‘Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields’, Biotechnology Advances, 36(7), pp. 1984-2016. doi: 10.1016/j.biotechadv.2018.08.008. [15] Padil, V. V. T. et al. (2015) ‘Synthesis, fabrication and antibacterial properties of a plasma modified electrospun membrane consisting of gum Kondagogu, dodecenyl succinic anhydride and poly (vinyl alcohol)’, Surface and Coatings Technology, 271. doi: 10.1016/j.surfcoat.2015.01.035.

[16] Venkateshaiah, A. et al. (2021) ‘Alkenyl succinic anhydride modified tree-gum kondagogu: A bio-based material with potential for food packaging’, Carbohydrate Polymers. Elsevier, 266, p. 118126. doi: 10.1016/J.CARBPOL.2021.118126.

[17] Padil, V. V. T. et al. (2016) ‘Electrospun fibers based on Arabic, karaya and kondagogu gums’, International Journal of Biological Macromolecules, 91 , pp. 299-309. doi: 10.1016/j.ijbiomac.2016.05.064.

[18] Kathleen Maleski, Vadym N. Mochalin, and Yury Gogotsi, Dispersions of Two- Dimensional Titanium Carbide MXene in Organic Solvents, Chemistry of Materials 2017 29 (4), 1632-1640, DOI: 10.1021/acs.chemmater.6b04830.

[19] Wan, Y. et al. (2021) ‘Ultrathin, Strong, and Highly Flexible Ti3C2Tx MXene/Bacterial Cellulose Composite Films for High-Performance Electromagnetic Interference Shielding’, ACS Nano, 15(5), pp. 8439-8449. doi: 10.1021/acsnano.0c10666.

[20] Ghidiu, M. et al. (2014) ‘Conductive two-dimensional titanium carbide “clay” with high volumetric capacitance’, Nature 2014516:7529. Nature Publishing Group, 516(7529), pp. 78-81. doi: 10.1038/nature13970.

[21] Han, M. et al. (2016) ‘Ti3C2 MXenes with Modified Surface for High-Performance Electromagnetic Absorption and Shielding in the X-Band’, ACS Applied Materials & Interfaces, 8(32), pp. 21011-21019. doi: 10.1021/acsami.6b06455.